Student debt in the U.S. now tops $1.2 trillion, spread among 37 million borrowers, 5.4 million of whom have already defaulted. Washington took notice this week, rolling out the usual non-solutions: On Monday, President Obama expanded a federal program that allows students to repay debt based on what they earn, eventually forgiving the balance. Taxpayers pay the rest. On Wednesday, Sen. Elizabeth Warren's idea to tax...